This invention relates to a light-driven semiconductor device, more specifically to a light-driven semiconductor device provided with a light-driven semiconductor element and a light guide for guiding a driving light signal from a light source to the element.
Newly developed are devices using a light activated thyristor (LASCR) as a light-driven semiconductor element which is controlled by a light signal. The devices of this type are characterized in that electrical insulation between the semiconductor element and a control section therefor is easy, and that unwanted operation is rarely caused by noise. In consideration of their character, these devices are expected to be applied to high-voltage power control systems.
For the following reasons, these light-driven semiconductor devices are subject a defect that it is difficult to control the locations of a light guide to guide a light signal to a light sensitive area of the semiconductor element and the light sensitive area. In these devices, the semiconductor element is generally tightened by cooling fins under high pressure, e.g. 100 kg/cm.sup.2 or more. Therefore, if the output end of the light guide is previously brought in contact with the light sensitive area, the contact portion may suffer severe distortion to cause malfunction of the device. Accordingly, the output end of the light guide must be separated from the light sensitive area by a distance through which the semiconductor element and/or light guide is shifted at the tightening. Practically, however, it is hard to keep them apart at such distance with high accuracy, and they are subject to variations in shifted distance. In consideration of these circumstances, the output end of the light guide and light sensitive area are separated by a considerably margin. As a result, it is difficult to align the optical axes of the two sections with high accuracy. Moreover, the output end is shifted even after location, so that the optical axes will possibly fail to align after manufacture. Furthermore, as the output end of the light guide becomes to apart from the light sensitive area of the semiconductor device the light transmitting efficiency therebetween becomes decrease.